PROBLEM TO BE SOLVED: To obtain a new stable enzyme consisting of a mutant creatine amidinohydrolase, improving a stability for a long period of time in a neutral buffer solution compared with that of a wild type, and useful for a measurement of creatine level in a blood for diagnosis of uremia, etc. ;SOLUTION: This is a stable new mutant type creatine amidinohydrolase having one, or two or more combined substituted positions out of glutamic acid at 15th position, and arginine at 104th and 135th positions in comparison with a wild type creatine amidinohydrolase expressed by the formula, and improving the stability for a long period of time in a neutral buffer solution, useful for the rapid and accurate detection of the creatine level in a blood or in a urine and used for the diagnosis of uremia, chronic nephritis, acute nephritis, gigantism, myotonic dystrophy, etc. This mutant enzyme is obtained by using a creatine amidinohydrolase gene originated from a bacterium belonging to the genus Alcaligenes, and creating the mutant type enzyme excellent in liquid state stability for a long period of time by using a protein engineering type technique.;COPYRIGHT: (C)1998,JPO
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